French authorities have opened an investigation into controversial Swiss-born Islamic scholar Tariq Ramadan after a French feminist accused him of sexual misconduct and sending her death threats.

Former Salafist Henda Ayari, 40, who now identifies as a secular feminist, filed a complaint with French authorities in Rouen accusing Ramadan of sexually harassing her, raping her, and issuing death threats towards her. The feminist activist also revealed that she had written about her experience in a book, but had been too fearful to print Ramadan's name, L'Expressreports.

On Friday, Ayari posted on her Facebook account about the situation saying: "I have been silent for several years because of fear, because by threatening to press charges for the rape I was a victim of, he did not hesitate to threaten me and to tell me also that he could go after my children. I got scared and kept quiet all this time."

" I really hope that other women victims, like me, dare to speak, and denounce this perverted guru who uses religion to manipulate women!" she wrote.

Finally, the former Islamic radical asked for support from her followers saying she expected that Ramadan would employ a "team of lawyers" against her.

Ramadan has been mostly silent on the issue but has launched a lawsuit against Ayari for defamation in the French courts.

Ramadan is not only a controversial Islamic scholar but is also the grandson of Muslim Brotherhood founder Hassan al-Banna. Many have accused Ramadan of saying one thing to Western audiences and another to his fellow Muslims in the Middle East and elsewhere.

In 2007, author Caroline Fourest wrote an entire book about the "doublespeak" of Ramadan in her work, Brother Tariq: The Doublespeak of Tariq Ramadan.

Ramadan was also banned from entering the United States by the George W. Bush administration in 2004 after it was alleged he donated to the Association de Secours Palestinien (ASP/ Palestinian Relief Organisation) from 1998 to 2002. The U.S. government considered the ASP a group that funded terrorism by giving some of their donations to the anti-Israel terrorist organisation Hamas which is proscribed in the U.S.

Mr Ramadan's U.S. travel ban was later lifted by then-Secretary of State Hillary Clinton in 2010 during the Obama administration.

The sexual assault allegations against Ramadan are just the latest in a slew of other allegations against prominent figures in the media and politicians following the revelations against Hollywood producer Harvey Weinstein.

Even the European Parliament has been rocked by allegations from staffers who have accused senior MEPs of sexual misconduct, including allegations against European Commission President Jean-Claude Juncker.